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MAINFRAMES

Model 10K488
Data Concentrator

and Associated "A" Cards (supplied with the 10K488):
Model 10A488 IEEE-488 Interface Card
Model 10A422 Communication Buffer Card

When synchronous data collection is not required, the Model 10K488 can accommodate up 19,000 analog input channels.  With synchronous sampling at intervals of 0.2 second, up to 9600 channels can be handled; at intervals of 0.1 second, up to 4800 channels.

The 10K488 provides a data communications interface between a digital computer connected to an IEEE-488 bus and up to nineteen System 10 "B-sized" mainframes with RS422 I/O capability.  Multiple 10K488 systems can be "cascaded" to handle even greater numbers of channels (up to fourteen 10K488's on a single IEEE-488 interface!)

As shown in the diagram below, the 10K488 consists of a rackmountable "A-sized" mainframe with 21 card slots (10K488 dimensions are identical to those of the Model 10K1C).

The Model 10A488 IEEE-488 Interface Card in Slot No. 21 provides the necessary IEEE-488 bus interchange protocol handling and the control of data transfer to and from up to 19 individual Model 10A422 Communication Buffer Cards occupying the 10K488's Slots 1 through 19.  Although the distance between the computer and the 10K488 is limited by IEEE-488 standards to about two meters, each RS422 "node" device can be as far as one kilometer (0.62 mile) from the Data Concentrator.

While it may serve as a communications interface for any RS422 device, the Model 10K488 was specifically designed to let multiple System 10 mainframe units "listen" simultaneously to a supervisory computer's request for data, and then "talk" (issue data) simultaneously to individual buffer cards for subsequent high-speed access by the computer.  In addition, the 10K488 provides a hardwire logic control line to each mainframe to trigger synchronous data collection, if desired.  The control line can be exercised by direct computer command.

In the above diagram, an independent "B-sized" mainframe (like the single one shown) is to be connected via RS422 cabling to each 10A422 card in the 10K488.  Each mainframe is to be equipped with a Model 10BACI-422 Auxiliary Computer Interface Card for direct connection to the respective 10A422 card (click here for a complete description of the 10BACI-422 and its use in synchronous data collection).  

Because of its inherent TRACK/HOLD capabilities, the Model 10A74-4C Strain Gage Conditioner is often used in 10K488 systems—along with the Model 10A1 Control Signal Card—to minimize "time-skew" effects during data collection that involves a large number of strain gage input signals.  In such a system, all strain gage channels can be triggered to "sample and hold" their data just prior to A/D conversion.  This ensures that all measurements are taken within a period of 10 microseconds.  A single Model 10A1 furnishes the sample and hold trigger for any given A-card "deck" (provided that no thermocouple conditioner cards are present)—or an external logic control signal can be introduced for this purpose.  The TRACK HOLD CONTROL (THC) command (see table below) is used to synchronize all of a given "node" mainframe's 10A1's to that node's internal scan cycle, thus ensuring that all channels in that mainframe "capture" their data at the very same instant.

Click here for an example of a 10K488-based system for high-speed aerospace strength and durability testing, using multiple 10A74-4C cards to allow as many as 4864 strain-gage input channels with virtually no time skew (a condition that is absolutely essential for the integrity of such large data sets). 

In addition to providing RS422 serial linkage, each Model 10A422 Communication Buffer Card has an internal logic-controlled RAM for storage of up to 2048 bytes of data being transferred from the card's RS422 port to the Model 10A488 IEEE-488 Interface Card and of up to 2048 bytes of data being transferred from the Model 10A488 to the RS422 port.  All data is stored in a strictly "first-in-first-out" (FIFO) manner.

In terms of IEEE-488 conventions, the Model 10K488 can be either a TALKER or a LISTENER.  It employs a standard "extended address" mode of operation.  The "primary address is the 10K488's address as a TALKER/LISTENER peripheral on the general IEEE-488 bus.  This address can be any integer from 0 through 30, and is set by means of switches on the Model 10A488 IEEE-488 Interface Card. The "secondary" (or "extended") address is latched and decoded to select one of the nineteen card slots in which Model 10A422 Communication Buffer Cards can be located—or all of these slots simultaneously.

When the 10K488 is the "primary addressed" LISTENER, and the "secondary" address is either 1-19 (to select a particular 10A422) or zero (to select all 10A422's), the data can be transferred from the computer to one or all of the RS422 devices connected to the 10K488.  When the 10K488 is the "primary addressed" TALKER, then the "secondary" address must be that of one of the 10A422 cards (i.e., a number from 1 through 19), to provide transfer of data to the computer from the single RS422 device connected to the addressed 10A422.

The commands used to initiate actual data interchanges between the computer and the 10K488 will depend on the computer's specific I/O handler.  The 10K488 responds to standard "clear" commands within the IEEE-488 language structure—e.g., INTERFACE CLEAR (IFC), SELECTED DEVICE CLEAR (SDC), DEVICE CLEAR (DCL).  Additional System 10 commands exist for synchronizing data collection to a "master" timing clock (see the table below).